Within the field of clamping devices for securing cutting inserts in tool holders, pin-type clamping devices are known which provide a means for securing a cutting insert within an insert receiving pocket of a tool holder and allow the cutting insert to be removed and replaced without the removal of any further components.
U.S. Pat. No. 3,314,126 discloses a pin-type locking mechanism for removably securing an indexable carbide insert in a tool holder, where one embodiment comprises an L-shaped locking member and a screw. The insert is located in a recess of the tool holder having a base surface and an end wall extending at a right angle to the base surface. The L-shaped locking member has a vertical leg, representing a clamping pin, extending above the base surface and into a central bore of the insert and a horizontal leg engaging a reduced diameter section of the screw. Rotation of the screw in one direction causes a pivoting action of the locking member whereby the clamping pin engages the central bore, thus forcing the insert against an end wall of the tool holder. This clamping force is directed solely in a direction towards the end wall.
This pin-type locking mechanism exerts no clamping force component in the direction of the base surface and relies on frictional forces between the vertical leg and the carbide insert and also between the carbide insert and the end wall to prevent any lifting or upward movement of the insert.
U.S. Pat. No. 3,908,255 discloses a pin-type clamping device for removably securing a cutting insert in a holder shank, comprising an angular lever arm and a clamping screw. The angular lever arm, situated in a recess below the insert site, has a first shank, representing a clamping pin, extending vertically through a central bore of the insert and a second shank extending horizontally in the same direction as a bottom support surface of the insert site. The clamping pin includes an upper projection and a middle projection, each extending laterally in the direction of the second shank. Rotation of the clamping screw to urge the second shank downwardly causes simultaneous rotation and sliding of the lever arm whereby the upper projection is urged against the top side of the cutting insert and the middle projection is urged against the inside of the central bore. The upper projection exerts a vertical clamping force on the cutting insert in the direction of the bottom support surface and the middle projection exerts a lateral clamping force on the cutting insert in the direction of a side support surface.
The vertical clamping force is exerted at a single point on the top side of the cutting insert.
It is an object of the present invention to provide an improved pin-type clamping device.
It is also an object of the present invention to provide an improved pin-type clamping device where the clamping pin has at least two upper clamping zones in clamping contact with the cutting insert to provide increased stability.
It is a further object of the present invention to provide an improved pin-type clamping device where each of the at least two upper clamping zones are located on independently resilient clamping fingers to provide increased stability whilst accounting for possible imperfections and inaccuracies of the cutting insert at the surface areas being clamped.